ICUs Seeing Less Central Line-Associated MRSA

The incidence of methicillin-resistant Staphylococcus aureus bloodstream infections related to the placement of central lines has declined in recent years in all major types of adult ICUs and has remained stable in nonneonatal pediatric ICUs, according to a report.

These findings suggest that prevention efforts are succeeding for this subgroup of MRSA patients, said Dr. Deron C. Burton and associates at the Centers for Disease Control and Prevention.

To characterize trends in MRSA incidence, the researchers assessed surveillance data reported to the CDC by 1,684 ICUs in 43 states from 1997 through 2007. In all, 33,587 central line-associated bloodstream infections were reported, of which 2,498 (7%) were MRSA.

The incidence of central line-associated bloodstream MRSA infections rose from 1997 to 2001, but then declined through 2007, resulting in an overall estimated decline of approximately 50% over the entire study period, the investigators said (JAMA 2009;301:727-36).

The incidence declined in recent years in all six major subtypes of adult ICUs: surgical; medical; combined medical-surgical without a major teaching affiliation; combined medical-surgical with a major teaching affiliation; cardiothoracic; and coronary units.

For nonneonatal pediatric ICUs, the incidence of central line-associated bloodstream MRSA infections remained stable from 1997 through 2007. These findings stand “in sharp contrast to trends in percent MRSA” (a different measure, representing pooled mean percent resistance), which can be “misleading.”

“The percent MRSA trend [erroneously] suggests a steady worsening” of the MRSA central line-associated bloodstream infections during the study period, Dr. Burton and colleagues noted.

In an editorial, Dr. Michael William Climo of Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Va., said that the decline in this specific subset of MRSA infections occurred against the backdrop of an increase in overall MRSA infections.

It is likely that this reduction was “related to a range of interventions that have been implemented during the last decade, including better hand hygiene practices, adoption of standardized line insertion and care practices, proper barrier precautions, improved catheter technology, and shorter periods of indwelling catheter use in patients,” Dr. Climo said (JAMA 2009;301:772-3).

The report offers “encouraging news,” commented Kathy Warye, CEO of the Association for Professionals in Infection Control and Epidemiology. The findings show that health care-associated infections “can be prevented in a very vulnerable group of patients when institutions consistently implement evidence-based prevention strategies,” Ms. Warye said in a statement. Noting that 67% of MRSA cases occur outside the ICU, she urged further action.

Central line-associated bloodstream MRSA infections declined approximately 50% in 1997-2007. (Above, scanning electron micrograph magnified 9560x.) CDC/Janice Haney Carr/Jeff Hageman, M.H.S.